Axiom3D:手动创建ManualObject与Mesh,以及如何使用Cg着色器语言

　　在开始正文前,先说下Axiom3D里遇到的二个BUG.

　　1.在启动axiom生成的程序中,我发现输出里总是有一些如"billboard_type","billboard_origin"这些不能解析,我开始还在想是不是文件格式版本过期或是啥的,反正后面我查了下,发现这些是有对应解析类的,在对比对应的Ogre相应位置代码,发现ParticleSystemRenderer在Ogre中是多重继承,C#天生不支持,但是我发现ScriptableObject本身是从DisposableObject继承的,那么只需要把ParticleSystemRenderer 从DisposableObject 继承改为从ScriptableObject 继承,然后在BillboardParticleRenderer类中方法SetParameter 修改成如下:

        public override bool SetParameter(string attr, string val)
        {
            try
            {
                Properties[attr] = val;
                return true;
            }
            catch (Exception e)
            {
                LogManager.Instance.Write(e.Message);
                return false;
            }
 
            //if ( this.attribParsers.ContainsKey( attr ) )
            //{
            //    var args = new object[2];
            //    args[ 0 ] = val.Split( ' ' );
            //    args[ 1 ] = this;
            //    this.attribParsers[ attr ].Invoke( null, args );
            //    //ParticleSystemRendererAttributeParser parser =
            //    //        (ParticleSystemRendererAttributeParser)attribParsers[attr];
 
            //    //// call the parser method
            //    //parser(val.Split(' '), this);
            //    return true;
            //}
            //return false;
        }

BillboardParticleRenderer修改

　　具体修改意义我简单说下,原来的修改格式是针对内部特性方法的,但是BillboardParticleRenderer类里全是内部特性类的,从前面的继承修改加这段代码,就是为了让BillboardParticleRenderer能自己查找自己的特性类并找到对应的设置方法.

　　2.这个BUG和ManualObject有关,我在设置ManualObject时,发现一些奇怪的问题,设置的颜色不能用,当时还以为是材质,灯光这些,后面全排除后,找到ManualObject里的CopyTempVertexToBuffer方法,发现有处逻辑不对.如下修改:

protected virtual void CopyTempVertexToBuffer()
        {
            this.tempVertexPending = false;
            var rop = this.currentSection.RenderOperation;
 
            if (rop.vertexData.vertexCount ==  && !this.currentUpdating)
            {
                // first vertex, autoorganise decl
                var oldDcl = rop.vertexData.vertexDeclaration;
                rop.vertexData.vertexDeclaration = oldDcl.GetAutoOrganizedDeclaration(false, false);
 
                HardwareBufferManager.Instance.DestroyVertexDeclaration(oldDcl);
            }
 
            ResizeTempVertexBufferIfNeeded(++rop.vertexData.vertexCount);
 
            var elemList = rop.vertexData.vertexDeclaration.Elements;
 
#if !AXIOM_SAFE_ONLY
            unsafe
#endif
            {
                // get base pointer
                var buf = BufferBase.Wrap(this.tempVertexBuffer);
                buf.Ptr = this.declSize * (rop.vertexData.vertexCount - );
 
                //var pFloat = buf.ToFloatPointer();
                //var pRGBA = buf.ToUIntPointer();
 
                foreach (var elem in elemList)
                {
                    var offest = elem.Offset;
                    buf.Ptr += offest;
                    var pFloat = buf.ToFloatPointer();
                    var pRGBA = buf.ToUIntPointer();
                    var idx = ;
                    RenderSystem rs;
                    int dims;
                    switch (elem.Semantic)
                    {
                        case VertexElementSemantic.Position:
                            pFloat[idx++] = this.tempVertex.position.x;
                            pFloat[idx++] = this.tempVertex.position.y;
                            pFloat[idx] = this.tempVertex.position.z;
                            break;
                        case VertexElementSemantic.Normal:
                            pFloat[idx++] = this.tempVertex.normal.x;
                            pFloat[idx++] = this.tempVertex.normal.y;
                            pFloat[idx] = this.tempVertex.normal.z;
                            break;
                        case VertexElementSemantic.TexCoords:
                            dims = VertexElement.GetTypeCount(elem.Type);
                            for (var t = ; t < dims; ++t)
                            {
                                pFloat[idx++] = this.tempVertex.texCoord[elem.Index][t];
                            }
                            break;
                        case VertexElementSemantic.Diffuse:
                            rs = Root.Instance.RenderSystem;
                            if (rs != null)
                            {
                                pRGBA[idx] = (uint)rs.ConvertColor(this.tempVertex.color);
                            }
                            else
                            {
                                pRGBA[idx] = (uint)this.tempVertex.color.ToRGBA(); // pick one!
                            }
                            break;
                        default:
                            // nop ?
                            break;
                    }
                }
            }
        }

CopyTempVertexToBuffer

　　简单来说,和原来地形的高度生成错误比较类似,把字节个数直接当做索引来用,ManualObject里的元素都是4个字节,还有一个简单的方法,直接让indx=elem.offset/4应该也是对的,但是我认为这种修改方法不算太好,如采用现在的方法.

　　现在开始正文,从ManualObject来说,ManualObject是Ogre模仿了Opengl里立即绘制模式的一种写法,但是他和立即绘制模式本质是不同的,写法虽然是这样,但是他也是采用缓冲区的方法,意思来说,就是写法让习惯写立即模式的人爽,效率也是,当然ManualObject里的有些元素写法顺序规定的和OpenGL的不一样.先来看一段代码,这段代码是我从Ogre论坛里考过来的,把里面的C++写法改变下就行了,非常容易.

        public static ManualObject CreateTetrahedron(Vector3 position, Single scale)
        {
            ManualObject manObTetra = new ManualObject("Tetrahedron");
            manObTetra.CastShadows = false;
 
            // render just before overlays (so all objects behind the transparent tetrahedron are visible)
            manObTetra.RenderQueueGroup = RenderQueueGroupID.Overlay - ; // = 99
 
            Vector3[] c = new Vector3[]; // corners
 
            // calculate corners of tetrahedron (with point of origin in middle of volume)
            Single mbot = scale * 0.2f;      // distance middle to bottom
            Single mtop = scale * 0.62f;     // distance middle to top
            Single mf = scale * 0.289f;    // distance middle to front
            Single mb = scale * 0.577f;    // distance middle to back
            Single mlr = scale * 0.5f;      // distance middle to left right
            //               width / height / depth
            c[] = new Vector3(-mlr, -mbot, mf);  // left bottom front
            c[] = new Vector3(mlr, -mbot, mf);  // right bottom front
            c[] = new Vector3(, -mbot, -mb);  // (middle) bottom back
            c[] = new Vector3(, mtop, );  // (middle) top (middle)
 
            // add position offset for all corners (move tetrahedron)
            for (Int16 i = ; i <= ; i++)
                c[i] += position;
 
            // create bottom
            manObTetra.Begin("floor", OperationType.TriangleList);
            manObTetra.Position(c[]);
            manObTetra.Color(ColorEx.Red);
            manObTetra.Position(c[]);
            manObTetra.Position(c[]);
            manObTetra.Triangle(, , );
            manObTetra.End();
            // create right back side
            manObTetra.Begin("edm/floor", OperationType.TriangleList);
            manObTetra.Position(c[]);
            manObTetra.Color(ColorEx.Green);
            manObTetra.Position(c[]);
            manObTetra.Position(c[]);
            manObTetra.Triangle(, , );
            manObTetra.End();
            // create left back side
            manObTetra.Begin("edm/floor", OperationType.TriangleList);
            manObTetra.Position(c[]);
            manObTetra.Color(ColorEx.Green);
            manObTetra.Position(c[]);
            manObTetra.Color(ColorEx.Red);
            manObTetra.Position(c[]);
            manObTetra.Color(ColorEx.Blue);
            manObTetra.Triangle(, , );
            manObTetra.End();
            // create front side
            manObTetra.Begin("BaseWhiteNoLighting", OperationType.TriangleList);
            manObTetra.Color(ColorEx.White);
            manObTetra.Position(c[]);
            manObTetra.Position(c[]);
            manObTetra.Position(c[]);
            manObTetra.Triangle(, , );
            manObTetra.End();
 
            return manObTetra;
 
        }

Tetrahedron ManualObject

　　这段代码也是我发现ManualObject里的颜色不能用的BUG的代码.我们从ManualObject里的代码来看一些注意事项,ManualObject是从Begin()方法调用后,根据第一个顶点到第二个顶点来生成顶点元素组成部分的.简单来说:

　　1.调用Begin方法后,需要最先调用Position方法,在第一个Position调用前如调用Color,Normal会引起元素实际与声明的组成部分对应不上.

　　2.在第一个Position和第二个Position之间出现的元素是这个缓冲区顶点的声明组成部分,如在第一个与第二个只出现了Color,那么你在第二个Position后声明Normal是无效的.

　　3.这个倒是OpenGL里的状态机有点像,在第一个Position与第二个Position调用Color,Normal这些后,不需要在第二个Position之后每次调用,如果调用,color,normal会采用新的值,直接看代码里的TempVertex类型tempVertex属性每次调用Position,Color,Normal就知道原因了.

　　下面放出上面代码生成效果图:

　　下面再给出一个立方体生成的ManualObject,和上面有些区别,大致就这二种写法.

        public static ManualObject CreateCube(Vector3 center, float length, bool bLine = false)
        {
            string material = "BaseWhiteNoLighting";
            ManualObject manual = new ManualObject("manualCube");
            Vector3[] positions = new Vector3[]{
                center + new Vector3(length, length, length),
                center + new Vector3(-length, length, length),
                center + new Vector3(-length, -length, length),
                center + new Vector3(length, -length, length),
                center + new Vector3(length, length, -length),
                center + new Vector3(-length, length, -length),
                center + new Vector3(-length, -length, -length),
                center + new Vector3(length, -length, -length)
            };
            ushort[] indexs = new ushort[]{
                ,,,,,,
                ,,,,,,
                ,,,,,,
                ,,,,,,
                ,,,,,,
                ,,,,,
            };
            if (bLine)
                manual.Begin(material, OperationType.LineList);
            else
                manual.Begin(material, OperationType.TriangleList);
            for (int i = ; i < positions.Length; i++)
            {
                manual.Position(positions[i]);
            }
            for (int i = ; i < indexs.Length; i++)
            {
                manual.Index(indexs[i]);
            }
            manual.End();
            return manual;
        }

ManualObject Cube

　　注意要让三角形与线同一顶点索引,每六个顶点索引中间二个是相同的,这样不生成线,但是三角形能正常生成,注意Ogre里也是逆时针.效果图就不发了.大家一看就知道是啥样的.

　　其实ManualObject与Mesh的区别不大,都是保存顶点状态与索引,ManualObject也有方法直接ConvertToMesh直接转为Mesh.不过要注意,ManualObject继承MovableObject,可以直接挂接到Node下,而Mesh只是一种资源,需要先以Entity为载体,再挂接到Node下,不过这样也使得Mesh更复杂,能完成与承载的功能也更多.

　　下面我们用Mesh来自定义一个模型,这个模型用来演示一个立方坐标轴,其中,XY与YZ可以用来展示,可以放入不同的材质,而XZ用来演示3D波动数据,这里我们用Cg加三维噪声来模拟,如这过程(柏林噪声实践(二) 水与火,顶点纹理拾取),最后大致效果如下:

图2:

　　代码分二部分，一部分是坐标轴的建立，这个主要是用到Mesh，一部分是每桢活动的数据,这个部分就用到Cg着色器代码，记的添加Cg着色器解析的插件。

　　下面是如何构建整个坐标轴的代码：

    public class Axis3D
    {
        public Mesh Self { get; set; }
        public Vector3 range;
 
        public Axis3D(string name, Vector3 range)
        {
            this.range = range;
            Mesh mesh = MeshManager.Instance.CreateManual(name, "General", null);
 
            float arrow1 = 30.0f;
            float arrow2 = 20.0f;
            float arrow3 = 3.0f;
            var vertices = new float[]{
                0.0f,0.0f,0.0f,//Origin
                range.x,0.0f,0.0f,//x
                0.0f,range.y,0.0f,//y
                0.0f,0.0f,range.z,//z
 
                range.x,range.y,0.0f,//xy plane
                range.x,0.0f,range.z,//xz plane
                0.0f,range.y,range.z,//yz plane
                range.x,range.y,range.z,//origin offest
 
                range.x+arrow1,0.0f,0.0f,
                range.x+arrow2,0.0f,-arrow3,
                range.x+arrow2,0.0f,arrow3,
 
                0.0f,range.y+arrow1,0.0f,
                -arrow3,range.y+arrow2,arrow3,
                arrow3,range.y+arrow2,-arrow3,
 
                0.0f,0.0f,range.z + arrow1,
                arrow3,0.0f,range.z+arrow2,
                -arrow3,0.0f,range.z+arrow2
            };
 
            mesh.SharedVertexData = new VertexData();
            mesh.SharedVertexData.vertexCount = ;
            var decl = mesh.SharedVertexData.vertexDeclaration;
            decl.AddElement(, , VertexElementType.Float3, VertexElementSemantic.Position);
            var vbuf = HardwareBufferManager.Instance.CreateVertexBuffer(decl.Clone(),
                mesh.SharedVertexData.vertexCount, BufferUsage.StaticWriteOnly);
            vbuf.WriteData(, vbuf.Size, vertices, true);
            mesh.SharedVertexData.vertexBufferBinding.SetBinding(, vbuf);
 
            SubMesh subMeshAxes = mesh.CreateSubMesh("axes");
            short[] indexs = new short[]{
                ,,
                ,,
                ,,
            };
            HardwareIndexBuffer ibuf = HardwareBufferManager.Instance.CreateIndexBuffer(IndexType.Size16, indexs.Length, BufferUsage.StaticWriteOnly);
            ibuf.WriteData(, ibuf.Size, indexs, true);
            subMeshAxes.useSharedVertices = true;
            subMeshAxes.indexData.indexBuffer = ibuf;
            subMeshAxes.indexData.indexCount = indexs.Length;
            subMeshAxes.indexData.indexStart = ;
            subMeshAxes.OperationType = OperationType.LineList;
 
            SubMesh subMeshArrow = mesh.CreateSubMesh("arrow");
            indexs = new short[]{
                ,,,
                ,,,
                ,,
            };
            ibuf = HardwareBufferManager.Instance.CreateIndexBuffer(IndexType.Size16, indexs.Length, BufferUsage.StaticWriteOnly);
            ibuf.WriteData(, ibuf.Size, indexs, true);
            subMeshArrow.useSharedVertices = true;
            subMeshArrow.indexData.indexBuffer = ibuf;
            subMeshArrow.indexData.indexCount = indexs.Length;
            subMeshArrow.indexData.indexStart = ;
            subMeshArrow.OperationType = OperationType.TriangleList;
 
            SubMesh subMeshPlaneXY = mesh.CreateSubMesh("planeXY");
            CreatePlaneXY(subMeshPlaneXY);
            SubMesh subMeshPlaneYZ = mesh.CreateSubMesh("planeYZ");
            CreatePlaneYZ(subMeshPlaneYZ);
 
            SubMesh subMeshPlaneXZ = mesh.CreateSubMesh("planeXZ");
            CreateRenderPlane(subMeshPlaneXZ);
 
            mesh.BoundingBox = new AxisAlignedBox(Vector3.Zero, range);
            mesh.BoundingSphereRadius = range.Length;
            mesh.Load();
 
            Self = mesh;
        }
 
        private void CreateAxis(SubMesh subMesh)
        {
            subMesh.useSharedVertices = false;
            subMesh.vertexData = new VertexData();
 
        }
 
        private void CreatePlaneXY(SubMesh subMesh)
        {
            int verticeLong = ;
            var vertices = new float[]{
                0.0f,0.0f,0.0f,//Origin
                0.0f,0.0f,
                range.x,0.0f,0.0f,//x
                1.0f,0.0f,
                0.0f,range.y,0.0f,//y
                0.0f,1.0f,
                range.x,range.y,0.0f,//xy plane
                1.0f,1.0f,
            };
            subMesh.useSharedVertices = false;
            subMesh.vertexData = new VertexData();
            subMesh.vertexData.vertexCount = verticeLong;
            var decl = subMesh.vertexData.vertexDeclaration;
            decl.AddElement(, , VertexElementType.Float3, VertexElementSemantic.Position);
            decl.AddElement(, VertexElement.GetTypeSize(VertexElementType.Float3), VertexElementType.Float2, VertexElementSemantic.TexCoords, );
            var buf = HardwareBufferManager.Instance.CreateVertexBuffer(decl.Clone(), verticeLong, BufferUsage.StaticWriteOnly);
            buf.WriteData(, buf.Size, vertices);
            subMesh.vertexData.vertexBufferBinding.SetBinding(, buf);
 
            var indexs = new short[]{
                ,,,
                ,,
            };
            var ibuf = HardwareBufferManager.Instance.CreateIndexBuffer(IndexType.Size16, indexs.Length, BufferUsage.StaticWriteOnly);
            ibuf.WriteData(, ibuf.Size, indexs, true);
            subMesh.indexData.indexBuffer = ibuf;
            subMesh.indexData.indexCount = indexs.Length;
            subMesh.indexData.indexStart = ;
            subMesh.OperationType = OperationType.TriangleList;
            subMesh.MaterialName = "axis3D/xy";
        }
 
        private void CreatePlaneYZ(SubMesh subMesh)
        {
            int verticeLong = ;
            var vertices = new float[]{
                0.0f,0.0f,0.0f,//Origin
                0.0f,0.0f,
                0.0f,range.y,0.0f,//y
                0.0f,1.0f,
                0.0f,0.0f,range.z,//z
                1.0f,0.0f,
                0.0f,range.y,range.z,//yz plane
                1.0f,1.0f,
            };
            subMesh.useSharedVertices = false;
            subMesh.vertexData = new VertexData();
            subMesh.vertexData.vertexCount = verticeLong;
            var decl = subMesh.vertexData.vertexDeclaration;
            decl.AddElement(, , VertexElementType.Float3, VertexElementSemantic.Position);
            decl.AddElement(, VertexElement.GetTypeSize(VertexElementType.Float3), VertexElementType.Float2, VertexElementSemantic.TexCoords, );
            var buf = HardwareBufferManager.Instance.CreateVertexBuffer(decl.Clone(), verticeLong, BufferUsage.StaticWriteOnly);
            buf.WriteData(, buf.Size, vertices);
            subMesh.vertexData.vertexBufferBinding.SetBinding(, buf);
 
            var indexs = new short[]{
                ,,,
                ,,
            };
            var ibuf = HardwareBufferManager.Instance.CreateIndexBuffer(IndexType.Size16, indexs.Length, BufferUsage.StaticWriteOnly);
            ibuf.WriteData(, ibuf.Size, indexs, true);
            subMesh.indexData.indexBuffer = ibuf;
            subMesh.indexData.indexCount = indexs.Length;
            subMesh.indexData.indexStart = ;
            subMesh.OperationType = OperationType.TriangleList;
            subMesh.MaterialName = "axis3D/yz";
        }
 
        public void Rendering(float delt)
        {
 
        }
 
        public void CreateRenderPlane(SubMesh subMesh)
        {
            var xc = 5.0f;
            var yc = 5.0f;
 
            var xr = (int)(range.x/xc) - ;
            var yr = (int)(range.z/yc) - ;
 
            var halfx = 0.0f;// xr * xc * 0.5f;
            var halfy = 0.0f;// yr * yc * 0.5f;
            var length = (xr + ) * (yr + ) * ;
            float[] vertices = new float[length];
 
            int index = ;
            for (int j = ; j <= yr; j++)
            {
                for (int i = ; i <= xr; i++)
                {
                    vertices[index++] = xc * i - halfx;
                    vertices[index++] = 0.0f;
                    vertices[index++] = yc * j - halfy;
 
                    //vertices[index++] = 0.3f;
                    //vertices[index++] = 0.3f;
                    //vertices[index++] = 0.3f;
                }
            }
 
            length = xr * yr * ;
            int[] indexs = new int[length];
            index = ;
            for (int j = ; j < yr; j++)
            {
                for (int i = ; i < xr; i++)
                {
                    indexs[index++] = (j + ) * (xr + ) + i;
                    indexs[index++] = (j + ) * (xr + ) + i;
                    indexs[index++] = (j + ) * (xr + ) + i + ;
 
                    indexs[index++] = (j + ) * (xr + ) + i + ;
                    indexs[index++] = (j + ) * (xr + ) + i;
                    indexs[index++] = (j + ) * (xr + ) + i + ;
                }
            }
 
            subMesh.useSharedVertices = false;
            subMesh.vertexData = new VertexData();
            subMesh.vertexData.vertexCount = (xr + ) * (yr + );
            var decl = subMesh.vertexData.vertexDeclaration;
            decl.AddElement(, , VertexElementType.Float3, VertexElementSemantic.Position);
            //decl.AddElement(0, VertexElement.GetTypeSize(VertexElementType.Float3), VertexElementType.Float3, VertexElementSemantic., 0);
            var buf = HardwareBufferManager.Instance.CreateVertexBuffer(decl.Clone(), subMesh.vertexData.vertexCount, BufferUsage.StaticWriteOnly);
            buf.WriteData(, buf.Size, vertices);
            subMesh.vertexData.vertexBufferBinding.SetBinding(, buf);
 
            var ibuf = HardwareBufferManager.Instance.CreateIndexBuffer(IndexType.Size32, indexs.Length, BufferUsage.StaticWriteOnly);
            ibuf.WriteData(, ibuf.Size, indexs, true);
            subMesh.indexData.indexBuffer = ibuf;
            subMesh.indexData.indexCount = indexs.Length;
            subMesh.indexData.indexStart = ;
            subMesh.OperationType = OperationType.TriangleList;
            subMesh.MaterialName = "noise3D";
        }
        //private void
    }

Axis3D Mesh

　　我们就简化轴，只用一条线和一个三角形来表示，XY与YZ面需要不同的材质，我们各分一个SubMesh更好化分。注意Mesh可以申请顶点缓冲区(所有SubMesh可以直接用这个顶点缓冲缓冲区)，但是没有索引缓冲区，意思就是Mesh本身不负责绘制元素，需要SubMesh绘制。而SubMesh由useSharedVertices确认是由采用SubMesh的索引缓冲区。这样做兼容性还是不错的，至少我想到一些文件格式都可以转化成Mesh这种结构。

　　在这个坐标轴了，Mesh建立了公共顶点，三条线和三个三角形都用到这个公共顶点。其中顶点缓冲区Ogre直接封装的是DX的那些类，申明VertexDeclaration与对应的VectexElement表明顶点元素的组成，前面的ManualObject在第一个Position与第二个Position之间申请的Color,Normal一样是这个过程，只是根据调用的方法，自动创建的VectexElement。而SubMesh如果表明直接用的是公共顶点，则只需要声明索引缓冲区就行了，申明索引缓冲区因为不需要指明顶点的构成元素，只需要说明是用32位字节还是16位字节，再对一些元素，如用法，连接模式行了。

　　至于建立XY，YZ面，则没用公共顶点缓冲区，那就需要自己申请自己的顶点缓冲区和索引缓冲区，申请过程和上面一样，需要指定useSharedVertices用false,对应的SubMesh可以自己指定对应的MaterialName。

　　最后则是XZ面，这个面，我们用来建立一些点，然后用Cg着色器代码控制顶点位置的Y轴，如何坐标有平滑性的波动，我们用到Noise，详细请看(柏林噪声实践(二) 水与火,顶点纹理拾取)，这里不多说了。

　　下面先给出对应的材质代码：

 // CG Vertex shader definition
 vertex_program noise3D_VS cg
 {
     source v4.cg
     entry_point main
     profiles vp40
     default_params
     {
         param_named_auto mvp worldviewproj_matrix
         param_named_auto time2 frame_time
         param_named_auto time1 time
         param_named_auto time3 time_0_x 10.0
     }
 }
 
 fragment_program noise3D_PS cg
 {
     source v4.cg
     entry_point fragmentShader
     profiles fp30
 }
 
 material noise3D
 {
     technique
     {
         pass
         {
             cull_hardware none
             vertex_program_ref noise3D_VS
             {
                 //param_named_auto time custom 0
             }
             texture_unit
             {
                 texture cloud.jpg
             }
             fragment_program_ref noise3D_PS
             {
             }
             texture_unit
             {
                 texture cloud.jpg
             }
         }
     }
 }

Material Noise3D

　　Cg着色器代码：

#define ONE 0.00390625
#define ONEHALF 0.001953125
 
float fade(float t) {
    //return t*t*(3.0-2.0*t); // Old fade
  return t*t*t*(t*(t*6.0-15.0)+10.0);
    // Improved fade
}
 
float noise(float3 P,sampler2D permTexture)
{
    float3 Pi = ONE*floor(P)+ONEHALF;
    float3 Pf = P-floor(P);
    // Noise contributions from (x=0, y=0), z=0 and z=1
  float perm00 = tex2D(permTexture, Pi.xy).a ;
    float3  grad000 = tex2D(permTexture, float2(perm00, Pi.z)).rgb * 4.0 - 1.0;
    float n000 = dot(grad000, Pf);
    float3  grad001 = tex2D(permTexture, float2(perm00, Pi.z + ONE)).rgb * 4.0 - 1.0;
    float n001 = dot(grad001, Pf - float3(0.0, 0.0, 1.0));
    // Noise contributions from (x=0, y=1), z=0 and z=1
  float perm01 = tex2D(permTexture, Pi.xy + float2(0.0, ONE)).a ;
    float3  grad010 = tex2D(permTexture, float2(perm01, Pi.z)).rgb * 4.0 - 1.0;
    float n010 = dot(grad010, Pf - float3(0.0, 1.0, 0.0));
    float3  grad011 = tex2D(permTexture, float2(perm01, Pi.z + ONE)).rgb * 4.0 - 1.0;
    float n011 = dot(grad011, Pf - float3(0.0, 1.0, 1.0));
    // Noise contributions from (x=1, y=0), z=0 and z=1
  float perm10 = tex2D(permTexture, Pi.xy + float2(ONE, 0.0)).a ;
    float3  grad100 = tex2D(permTexture, float2(perm10, Pi.z)).rgb * 4.0 - 1.0;
    float n100 = dot(grad100, Pf - float3(1.0, 0.0, 0.0));
    float3  grad101 = tex2D(permTexture, float2(perm10, Pi.z + ONE)).rgb * 4.0 - 1.0;
    float n101 = dot(grad101, Pf - float3(1.0, 0.0, 1.0));
    // Noise contributions from (x=1, y=1), z=0 and z=1
  float perm11 = tex2D(permTexture, Pi.xy + float2(ONE, ONE)).a ;
    float3  grad110 = tex2D(permTexture, float2(perm11, Pi.z)).rgb * 4.0 - 1.0;
    float n110 = dot(grad110, Pf - float3(1.0, 1.0, 0.0));
    float3  grad111 = tex2D(permTexture, float2(perm11, Pi.z + ONE)).rgb * 4.0 - 1.0;
    float n111 = dot(grad111, Pf - float3(1.0, 1.0, 1.0));
    // Blend contributions along x
  float4 n_x = lerp(float4(n000, n001, n010, n011), float4(n100, n101, n110, n111), fade(Pf.x));
    // Blend contributions along y
  float2 n_xy = lerp(n_x.xy, n_x.zw, fade(Pf.y));
    // Blend contributions along z
  float n_xyz = lerp(n_xy.x, n_xy.y, fade(Pf.z));
    return n_xyz;
}
 
float turbulence(int octaves, float3 P, float lacunarity, float gain,sampler2D permTexture)
{
    float sum = ;
    float scale = ;
    float totalgain = ;
    for(int i=;i<octaves;i++){
        sum += totalgain*noise(P*scale,permTexture);
        scale *= lacunarity;
        totalgain *= gain;
    }
 
    return abs(sum);
}
 
struct v_Output {
    float4 position : POSITION;
    //float pc : TEXCOORD0;
    float2 pc : TEXCOORD0;
};
 
v_Output main(float3 position : POSITION,
                           uniform float4x4 mvp,
                           uniform float time1,
                           uniform float time2,
                           uniform float time3,
                           uniform sampler2D permTexture)
{
    v_Output OUT;
    float time = time3 + time1 + time2 * ;
    float3 pf = float3(position.xz,time);
    //float ty = noise(pf,permTexture);
    //水
    //float ty = turbulence(4,pf,2,0.5,permTexture);
    //float yy = ty * 0.5 + 0.5;
    //火
    float ty = turbulence(,pf,0.6,,permTexture);
    float yy = ty * 0.5;
    float4 pos = float4(position.x,yy,position.z,);
    OUT.pc = float2(position.x*0.01,position.z*0.01);
    //float4 pos = float4(position.x,50,position.z,1);
    OUT.position = mul(mvp,pos);
    //OUT.pc = yy;
    return OUT;
}
 
struct f_Output {
    float4 color : COLOR;
};
 
f_Output fragmentShader(v_Output vin,uniform sampler2D texture)
{
    f_Output OUT;
    OUT.color = tex2D(texture, vin.pc);
    OUT.color = OUT.color + float4(0.1,0.1,0.1,0.1);
    return OUT;
}

Cg Noise3

　　这里简单说明一下材质代码，相关着色器代码具体意思大家移步前面链接。

　　在noise3D material中，vertex_program与fragment_program分别指定顶点和片断着色器，source指定相对路径的源文件代码位置，而entry_point指定当前着色器主函数，profiles指定硬件要求，因为我们用到纹理拾取，顶点着色器内纹理，所以在opengl下需要满足vp40才行，相关profiles对应硬件与说明请看Declaring Vertex/Geometry/Fragment Programs，vp40要求比较新的显卡。其中default_params相当于我们给着色器中uniform变量设定的初始值，param_named_auto指明由Ogre内部自动更新，详情请看Using Vertex/Geometry/Fragment Programs in a Pass。大家对应一下顶点着色器中的default_params参数与Cg里的代码，就能看明白是怎么个意思，Ogre这一块封装的相当不错，用起来没有别扭的感觉，并且还非常方便与人性化。在对应的material,对应Pass里指明vertex_program_ref与fragment_program_ref与前面对应，其中着色器需要的纹理直接紧接着对应的着色器后添加texture_unit就行，个数对应上。

　　总的来说，这里主要测试自动创建一些简单模型与着色器代码的基本用法，都是比较基础的，也可以看出Ogre对于这里的处理还是相当不错，方便又容易理解。